Composite fusible explosive compositions based on TNT constitute an important class of military explosives. Examples of such composite explosive include Composition B (RDX - cyclotrimethylenetrinitramine and TNT - 2,4,6-trinitrotoluene), Cyclotols (RDX and TNT in ratios of 75/25, 70/30, 65/35, and 60/40 resp.), Amatol (NH.sub.4 NO.sub.3 and TNT), Amatex (NH.sub.4 NO.sub.3, RDX and TNT), Kalatol (KNO.sub.3 and TNT), Baratol (BA(NO.sub.3).sub.2 and TNT), Pentolite (pentaerythritol tetranitrate (PETN) and TNT) and Baronal (Ba(NO.sub.3).sub.2, aluminum and TNT). Such compositions are generally prepared by stirring the powdered solid components, which include such materials as RDX, HMX (cyclotetramethylenetetranitramine), PETN, NH.sub.4 NO.sub.3, KNO.sub.3, Ba(NO.sub.3).sub.2, Pb(NO.sub.3).sub.2, KClO.sub. 4, NH.sub.4 ClO.sub.4 and aluminum metal and mixtures thereof which are essentially insoluble in TNT, with the molten TNT until a homogeneous dispersion or slurry is obtained. The molten slurry is loaded into shells or other ordnance items by pouring into the cavity and allowing the melt to cool and solidify. Such slurries, which in concentrated cases are very viscous and difficult to pour, exhibit undesirable segregation or settling of the solids during the period required for cooling and solidification, thereby producing casts of non-uniform composition, which adversely affects the explosive and ballistic characteristics of the item. The rate of settling or segregation increases as the difference in density between the solid components and the molten TNT increases.
In the past various methods have been employed to overcome the aforesaid solids segregation problem, but such methods have not been entirely satisfactory or are of only limited suitability. The problem has been acceptably overcome by using small items and melting the composite TNT explosive to just above the melting point of the TNT and stirring the mass during the cooling of the melt, or by solidifying the small items rapidly. In the case of large items, the problem has been met in less satisfactory manner by introducing solidified chunks of the composite explosive into the partially loaded melt in the warhead to reduce the time required for the melt to solidify completely. It has also been proposed to incorporate small amounts of additives, such as finely divided silica, silicone resins, nitrocellulose and other cellulosic resins, to improve the suspension of the solid components in the TNT slurry. However, such additives are either not sufficiently effective or affect other properties of the slurry of cast explosive undesirably.